Add types to ErrorFactory message parameters

Author: mmermerkaya

packages/util/src/errors.ts

@@ -103,18 +103,25 @@ export class FirebaseError extends Error {
   }
 }
 
-export class ErrorFactory<ErrorCode extends string> {
+export class ErrorFactory<
+  ErrorCode extends string,
+  ErrorParams extends { readonly [K in ErrorCode]?: ErrorData } = {}
+> {
   constructor(
     private readonly service: string,
     private readonly serviceName: string,
     private readonly errors: ErrorMap<ErrorCode>
   ) {}
 
-  create(code: ErrorCode, data: ErrorData = {}): FirebaseError {
+  create<K extends ErrorCode>(
+    code: K,
+    ...data: K extends keyof ErrorParams ? [ErrorParams[K]] : []
+  ): FirebaseError {
+    const customData = data[0] || {};
     const fullCode = `${this.service}/${code}`;
     const template = this.errors[code];
 
-    const message = template ? replaceTemplate(template, data) : 'Error';
+    const message = template ? replaceTemplate(template, customData) : 'Error';
     // Service Name: Error message (service/code).
     const fullMessage = `${this.serviceName}: ${message} (${fullCode}).`;
 
@@ -123,14 +130,14 @@ export class ErrorFactory<ErrorCode extends string> {
     // Keys with an underscore at the end of their name are not included in
     // error.data for some reason.
     // TODO: Replace with Object.entries when lib is updated to es2017.
-    for (const key of Object.keys(data)) {
+    for (const key of Object.keys(customData)) {
       if (key.slice(-1) !== '_') {
         if (key in error) {
           console.warn(
             `Overwriting FirebaseError base field "${key}" can cause unexpected behavior.`
           );
         }
-        error[key] = data[key];
+        error[key] = customData[key];
       }
     }
 

packages/util/test/errors.test.ts

@@ -32,7 +32,17 @@ const ERROR_MAP: ErrorMap<ErrorCode> = {
     'I decided to use {$code} to represent the error code from my server.'
 };
 
-const ERROR_FACTORY = new ErrorFactory<ErrorCode>('fake', 'Fake', ERROR_MAP);
+interface ErrorParams {
+  'file-not-found': { file: string };
+  'anon-replace': { repl_: string };
+  'overwrite-field': { code: string };
+}
+
+const ERROR_FACTORY = new ErrorFactory<ErrorCode, ErrorParams>(
+  'fake',
+  'Fake',
+  ERROR_MAP
+);
 
 describe('FirebaseError', () => {
   it('creates an Error', () => {
@@ -68,7 +78,9 @@ describe('FirebaseError', () => {
   });
 
   it('uses the key in the template if the replacement is missing', () => {
-    const e = ERROR_FACTORY.create('file-not-found', { fileX: 'foo.txt' });
+    const e = ERROR_FACTORY.create('file-not-found', {
+      fileX: 'foo.txt'
+    } as any);
     assert.equal(e.code, 'fake/file-not-found');
     assert.equal(
       e.message,